Database Reference
In-Depth Information
Our point of departure is the data structure of proplets. For purposes of stor-
age and retrieval, a proplet is specified uniquely
1
by its
core
and
prn
val-
ues (primary key). This suggests a two-dimensional database schema, as in a
classic network database (cf. Elmasri and Navathe 1989). A column of owner
records is in the alphabetical order of their core values. Each owner record
is preceded by a list of member records, distinguished between in terms of
their
prn
values. However, instead of using member and owner
records
we use
equivalent member and owner
proplets
. The result is called a Word Bank.
As an example, consider storing the proplets of the content 3.2.1:
4.1.1 S
TORING THE PROPLETS OF
3.2.1
IN A
W
ORD
B
ANK
member proplets
now front
owner proplets
...
...
⎡
⎣
⎤
⎦
⎡
⎣
⎤
⎦
noun: John
cat: nm
fnc: ...
prn: 610
noun: John
cat: nm
fnc: know
prn: 625
core: John
...
...
...
⎡
⎣
⎤
⎦
⎡
⎣
⎤
⎦
noun: Julia
cat: nm
fnc: ...
prn: 605
noun: Julia
cat: nm
fnc: know
prn: 625
core: Julia
...
...
...
⎡
⎣
⎤
⎦
⎡
⎣
⎤
⎦
verb: know
cat: decl
arg: ...
prn: 608
verb: know
cat: decl
arg: Julia John
prn: 625
core: know
...
... ...
An owner proplet and the preceding member proplets form a
token line
.The
proplets in a token line all have the same core value and are in the temporal
2
order of their arrival, reflected by their
prn
values.
In contrast to the task of designing a practical schema for arranging the topics
in a private library, the sorting of proplets into a Word Bank is simple and me-
chanical. The letter sequence of a proplet's core value completely determines
its token line for storage: the storage location for any new arrival is the penul-
timate position in the corresponding token line, called the
now front
.
A Word Bank is content-addressable because no separate index (inverted
file) is required. Furthermore, a Word Bank is scalable (a property absent or
problematic in some other content-addressable systems). The cost of insertion
is constant, independent of the size of the stored data, and the cost of retriev-
ing a specified proplet grows only logarithmically with the data size (external
access) or is constant (internal access). External access to a proplet requires(i)
1
Propositions containing two or more proplets with the same values, as in
Suzy loves Suzy
, require
extra attention. They constitute a special case which (i) occurs very rarely and (ii) is disregarded here
because it is easily handled.
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